Objective: Individuals' cognitive abilities predict functional outcomes following
traumatic brain injury (TBI). However, it is not known to what extent concurrent
cognitive abilities affect the magnitude or the rate of functional recovery. The
current study modeled the progression of functional outcome as it related to
background, injury severity, and cognitive variables over the first year
postinjury. Method: This study comprised 111 individuals with moderate-to-severe
TBI assessed on average at 3, 6, and 13 months postinjury. In addition, 79
healthy controls were assessed at a single time point. Each assessment consisted
of an administration of a neuropsychological battery-comprising measures of
memory, information processing speed, and executive functions-as well as an
administration of the Mayo-Portland Adaptability Inventory to examine functional
outcomes. Results: Older age, lower levels of education, and greater days of
posttraumatic amnesia were associated with poorer functional outcomes. The
addition of cognitive variables resulted in better models than simply considering
background and injury severity variables. However, the results showed that the
model comprising executive functions best characterized the progression of
functional outcomes. Conclusions: The findings indicate that consideration of
cognitive ability, rather than reliance on demographic and injury severity
variables, provide a more accurate representation of functional outcome over the
first year postinjury. In addition, the results suggest that specific cognitive
domains, particularly executive functions, are likely to have the strongest
effect on functional outcomes.